Strength endurance training - here's how you go about it

Defining strength endurance is not that easy. This is because training focuses on either endurance or strength. Sports science would rather call the term "local anaerobic dynamic or static endurance". But why?If less than 15 to 20 per cent of the maximum force is used, the muscle tension is still so low that the capillaries are not compressed and blood can flow freely to supply the muscle with oxygen and nutrients. In this case it is still aerobic work or endurance. Only from 30 per cent of the maximum force does the compression of the supplying blood vessels begin and only from 50 to 60 per cent of the maximum force is there a blood flow stop.During training, the transition from aerobic to anaerobic work is usually fluid. Both the increase in the frequency of movement and the increase in the intensity of the load and the resulting compression of the blood vessels lead to more and more anaerobic metabolic processes. The load time is correspondingly short, during which the work is mainly anaerobic. It is between 6 and 120 seconds. With longer exertion, more and more aerobic processes are started, but the intensity decreases.

Basically, strength endurance plays an important role in all sports in which an intense performance must be maintained in a rather small part of the musculature for a maximum of two minutes at a time. 

If you want to train strength endurance, you should know the limiting factors. These include:

• amount of energy that can be developed anaerobically: It depends on the size of the usable energy depot and the enzyme stock in the muscle cell. Enzymes are necessary for energy metabolism and their number can be trained. This means that the amount of energy that can be expended can also be increased. More enzymes therefore have a positive effect on strength endurance.
• local and central fatigue: In the muscle, metabolic end products such as lactate accumulate during anaerobic exercise and the cellular environment becomes more acidic. This in turn limits the work of the enzymes that supply the energy for muscle work. At the same time, the pH value in the blood drops (=it also becomes more acidic), so that the central nervous system sends more inhibitory impulses than command impulses and the work is stopped. If your muscles fatigue more quickly, you will have correspondingly less strength endurance. The removal and recycling of lactate can be improved through training, as can the ability to withstand acidic pH levels. The latter can be described with the term "mental fatigue resistance". You probably also know the terms "stamina" or "tempo strength" from sports.
  
• Maximum strength: Under 15% load intensity, strength endurance is independent of maximum strength. The higher the load intensity, the more relevant maximum strength is for strength endurance performance. Example: One person can bench press 80 kg, another 50 kg. If a dumbbell of 40 kg is to be pressed as often as possible per time unit, the person with 80 kg 1RM will be better. If a dumbbell of 4 kg is to be pressed, it remains open who performs better, as aerobic endurance is the performance-limiting factor here. Overall, maximum strength (in the range above 15% of 1RM) is a very decisive factor for strength endurance performance. Because: the higher the maximum strength, the lower the relative intensity.
  

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There is no standardised and objective measurement procedure as there is for determining maximum or speed strength.Basically, strength endurance can be determined by the time for which a muscle or muscle group can perform static work at a defined load intensity at will. Or the time is measured within which a defined number of contractions/min can be performed against a defined resistance until the movement amplitude or frequency cannot be maintained.There are basically two possibilities: Either the intensity is determined and it is measured how long the load can be maintained or the time is determined and it is measured how much power can be produced on average in this time.

• The intensity should be chosen so that the duration of the exercise is 6-120 seconds. This is because anaerobic metabolic processes predominantly take place within this time span.
• The measurement methods are relatively broad, not very standardised and extremely dependent on the motivation of the test person.
• Is it an absolute or relative measurement? In other words: measurement of the maximum possible number of repetitions with a fixed load independent of the 1RM of the person OR measurement of the maximum possible number of repetitions with a percentage load (e.g. 50% 1RM).

An example from the NFL Combine: In this example a bench press with 102kg is performed until muscular fatigue is reached (absolute load) to measure strength endurance. Example of relative measurement: Athlete A 1RM of 130kg, Athlete B 1 RM of 150kg

You can train strength endurance in the weight room, e.g. during the bench press. Generally, 50-60% of 1RM is recommended for 15-30 repetitions when strength endurance is measured relatively as a given percentage of 1RM. You should keep the following in mind:

• maximum load duration of two minutes to stay in the anaerobic zone.
• improvements on the energetic level are your goal: anaerobic glycolysis and endurance of high lactate values.

However, to increase strength endurance, it can also be very helpful to improve maximum strength. The following example illustrates which of these is more useful in which situation.

Example: Previously I was able to bench press 50 kg 30x with a 1RM of 100 kg. The 50 kg therefore correspond to 50% of the 1RM. I complete a 6-week training with 3x30 bench presses with 50 kg. My 1RM increases to 110kg. Then I test the strength endurance now with 50 kg (=45% 1RM) or with 55 kg (still 50% 1RM). With the latter approach, the aforementioned training method has the greatest increase in performance. With the absolute method, depending on the athlete, the increase in maximum strength with appropriate training in the 1-5 repetition range has at least as good a performance improvement.This leads to: A workout that trains strength endurance with 50-60% of the 1RM for 15-30 repetitions on the one hand and focuses on maximum strength on the other hand is most successful. The choice of training method should be based on your strength/weakness profile. If you already have good maximum strength and have trained this over a long period of time, a new stimulus and focus on the strength endurance method is useful to improve strength endurance.

Strength endurance training can boost your performance in many sports. However, it is important that you also utilise the potential of your maximum strength and that the exercises specifically match the target movements required for your sport.